The invention is directed to an electrolytic bath for the deposition of high gloss white gold coating having 2-10 g/l of gold in the form of a sulfide complex, 2-40 g/l of alkali sulfite, 2-40 g/l of a complex former, 1-10 g/l of nickel and 1-20 g/l of cadmium, in each case in the form of a water soluble salt.
For the corrosion resistant coating of commodities made of metal, as e.g. eyeglass frames, clockcases, bracelets or lighters there are frequently needed galvanic (electrolytic) coatings of white gold. There are known white gold baths which contain the gold as sulfite complex and besides contain alkali sulfite and ethylenediaminetetraacetic acid. As alloying metals there are customarily used copper, nickel and/or cadmium, as glossing agent, e.g. phosphonic acids (German OS No. 2334813 and related Olivier U.S. Pat. No. 3,883,409. The entire disclosure of Olivier and German OS No. 2042127 referred to therein are hereby incorporated by reference and relied upon). These baths permit the deposition of thick, ductile white gold coatings having a gold content of around 75%. However, it is a disadvantage that in the operation of such baths slight impurities of heavy metals such as lead or iron and cyanide ions or cyanide complex in many cases can lead to distrubances which unfavorably effect the gloss of the coating.
Therefore it was the problem of the present invention to provide an electrolytic bath for the deposition of high gloss white gold coatings having 2-10 g/l of gold in the form of a sulfite complex, 2-10 g/l of alkali sulfite, 2-40 g/l of a complex former, 1-10 g/l of nickel and 1-20 g/l of cadmium, in each case in the form of a water soluble salt, which is not sensitive to heavy metal and cyanide impurities.